112 lines
3.0 KiB
Markdown
112 lines
3.0 KiB
Markdown
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## [DEMO](https://tonejs.github.io/MidiConvert/)
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MidiConvert makes it straightforward to work with MIDI files in Javascript. It uses [midi-file-parser](https://github.com/NHQ/midi-file-parser) to decode MIDI files and [jsmidgen](https://github.com/dingram/jsmidgen) to encode MIDI files.
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```javascript
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//load a midi file
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MidiConvert.load("path/to/midi.mid", function(midi){
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console.log(midi)
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})
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```
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### Format
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The data parsed from the midi file looks like this:
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```javascript
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{
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// the transport and timing data
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header : {
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bpm : Number, // the tempo, e.g. 120
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timeSignature : [Number, Number], // the time signature, e.g. [4, 4],
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PPQ : Number // the Pulses Per Quarter of the midi file
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},
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// an array of midi tracks
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tracks : [
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{
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name : String, // the track name if one was given
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notes : [
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{
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midi : Number, // midi number, e.g. 60
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time : Number, // time in seconds
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note : String, // note name, e.g. "C4"
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velocity : Number, // normalized 0-1 velocity
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duration : String // duration between noteOn and noteOff
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}
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],
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//midi control changes
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controlChanges : {
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//if there are control changes in the midi file
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'91' : [
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{
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number : Number // the cc number
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time : Number, // time in seconds
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value : Number // normalized 0-1
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}
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],
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},
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instrument : String //the instrument if one is given
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}
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]
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}
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```
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### Raw Midi Parsing
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If you are using Node.js or have the raw binary string from the midi file, just use the `parse` method:
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```javascript
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fs.readFile("test.mid", "binary", function(err, midiBlob){
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if (!err){
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var midi = MidiConvert.parse(midiBlob)
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}
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})
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```
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### Encoding Midi
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You can also create midi files from scratch of by modifying an existing file.
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```javascript
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//create a new midi file
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var midi = MidiConvert.create()
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//add a track
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midi.track()
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//chain note events: note, time, duration
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.note(60, 0, 2)
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.note(63, 1, 2)
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.note(60, 2, 2)
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//write the output
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fs.writeFileSync("output.mid", midi.encode(), "binary")
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```
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### Tone.Part
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The note data can be easily passed into [Tone.Part](http://tonejs.github.io/docs/#Part)
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```javascript
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var synth = new Tone.PolySynth(8).toMaster()
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MidiConvert.load("path/to/midi.mid", function(midi){
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//make sure you set the tempo before you schedule the events
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Tone.Transport.bpm.value = midi.bpm
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//pass in the note events from one of the tracks as the second argument to Tone.Part
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var midiPart = new Tone.Part(function(time, note){
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//use the events to play the synth
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synth.triggerAttackRelease(note.name, note.duration, time, note.velocity)
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}, midi.tracks[0].notes).start()
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//start the transport to hear the events
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Tone.Transport.start()
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})
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```
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### Acknowledgment
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MidiConvert uses [midi-file-parser](https://github.com/NHQ/midi-file-parser) which is ported from [jasmid](https://github.com/gasman/jasmid) for decoding MIDI data and and [jsmidgen](https://github.com/dingram/jsmidgen) for encoding MIDI data.
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